Interface: ST18000NM000J lists SATA 6 Gb/s; WD181KRYZ lists SATA 6Gb/s.
Cache (MB): ST18000NM000J lists 256; WD181KRYZ lists 512.
Sustained transfer (up to MB/s): ST18000NM000J lists 270; WD181KRYZ lists 269.

A larger cache, higher RPM or higher advertised sequential speed alone does not establish which drive is better for your workload.

Specifications side by side

Show differences only

Manufacturer specifications for ST18000NM000J and WD181KRYZ
Specification	ST18000NM000J	WD181KRYZ
Manufacturer	Seagate	Western Digital
Product family	Exos X18	WD Gold
Model number	ST18000NM000J	WD181KRYZ
Capacity (TB)	18	18
RPM	7200	7200
Interface	SATA 6 Gb/s	SATA 6Gb/s
Cache (MB)	256	512
Form factor	3.5-inch	3.5-inch
Average idle power (W)	5.3	Not recorded
Power-on hours per year	8760	Not recorded
Manufacturer limited warranty	5 years (eligible new drives)	5 years (eligible new drives)
Sustained transfer (up to MB/s)	270	269
Recording	Not recorded	CMR
Workload rating (TB/year)	Not recorded	550
Logical sector size (bytes)	Not recorded	512
Physical sector size (bytes)	Not recorded	4096

Compatibility and buying checks

Compare new and renewed offers separately. The manufacturer specification does not guarantee the warranty or return policy of a marketplace seller.

Reviewed 2026-09-07. Published specifications; no independent benchmark or failure-rate claim.

Reviewed 2026-08-21. Published specifications; no independent benchmark or failure-rate claim.